Category Archives: Notes

Regression to the mean and chance

I think that Kahneman's body of work is of the most interesting contribution to psychology and economics of the last  decades. Kahneman's book "Thinking Fast and Slow" is a must read for anyone interested in understanding a little bit little about how human(s) (dynamics) work. Kahneman gives the impression in the book that the majority of his (and Amos Tversky's) results have been - after the usual initial struggle - well-accepted by the scientific community. This is far from the truth, but the book is a must read anyway.

By the way, Peter Kareiva, one the most influential conservation biologists in the world, asked during his seminar at UCSC this past January 2013 who among the audience had read Michael Sandel's last book "What Money Can't Buy: The Moral Limits of Markets". I was the only one. For me, it is absolutely necessary as as scientist to keep up with the psychological/philosophical/economic literature, and it is even more necessary for scientists dealing with conservation issues and projects. If you are not engaged in the current psychological/philosophical/economic discourse, you are bound to be irrelevant. No other options.

Here are some of the notes:

"Subjects’ unwillingness to deduce the particular from the general was matched only by their willingness to infer the general from the particular."

"[On regression to the mean] Because we tend to be nice to other people when they please us and nasty when they do not, we are statistically punished for being nice and rewarded for being nasty."

“She says experience has taught her that criticism is more effective than praise. What she doesn’t understand is that it’s all due to regression to the mean.”

I agree 100% with this one below. The contribution of chance is way underestimated.

"A few years ago, John Brockman, who edits the online magazine Edge, asked a number of scientists to report their “favorite equation.” These were my offerings: success = talent + luck great success = a little more talent + a lot of luck."

"[Google's founders] a year after founding Google, they were willing to sell their company for less than $1 million, but the buyer said the price was too high."

"Professional investors, including fund managers, fail a basic test of skill: persistent achievement."

"The human mind does not deal well with nonevents."

"Indeed, the statistician David Freedman used to say that if the topic of regression comes up in a criminal or civil trial, the side that must explain regression to the jury will lose the case. Why is it so hard? The main reason for the difficulty is a recurrent theme of this book: our mind is strongly biased toward causal explanations and does not deal well with “mere statistics.”"

"The goal of venture capitalists is to call the extreme cases correctly, even at the cost of overestimating the prospects of many other ventures. For a conservative banker making large loans, the risk of a single borrower going bankrupt may outweigh the risk of turning down several would-be clients who would fulfill their obligations. In such cases, the use of extreme language (“very good prospect,” “serious risk of default”) may have some justification for the comfort it provides, even if the information on which these judgments are based is of only modest validity."

Showers are always good.

"However, it is clear that for the large majority of individual investors, taking a shower and doing nothing would have been a better policy than implementing the ideas that came to their minds."

"The diagnostic for the existence of any skill is the consistency of individual differences in achievement. The logic is simple: if individual differences in any one year are due entirely to luck, the ranking of investors and funds will vary erratically and the year-to-year correlation will be zero. Where there is skill, however, the rankings will be more stable. The persistence of individual differences is the measure by which we confirm the existence of skill among golfers, car salespeople, orthodontists, or speedy toll collectors on the turnpike."

"Experienced radiologists who evaluate chest X-rays as “normal” or “abnormal” contradict themselves 20% of the time when they see the same picture on separate occasions."

"But this is what always happens when a project ends reasonably well: once you understand the main conclusion, it seems it was always obvious."

"(the classic “triumph of hope over experience”)"

"The chances that a small business will thesurvive for five years in the United States are about 35%."

"I have yet to meet a successful scientist who lacks the ability to exaggerate the importance of what he or she is doing, and I believe that someone who lacks a delusional sense of significance will wilt in the face of repeated experiences of multiple small failures and rare successes, the fate of most researchers."

Do yourself a favor and read the whole book.


General audience and scientific audience

Bob Paine, one the most important ecologists of the last 50 years, comments on his contribution to science.

"[Question]Did you know right away how big of an impact it would have? People spend their entire lives studying your theories.

Oh yes they do, and that produces its own headaches. But here’s a story. When that (keystone species) paper came out, I ordered 600 reprints, they went instantly. I went back to American Naturalist and got 600 more, and they went instantly, I went back again and they said sorry, they couldn’t print anymore. Later, I went home and  talked with my mother, who at  that time was writing small contributions for the New York Times science page, and I bragged, “Mother! Look at how successful this paper has been.” She said: “Son that’s OK, but I have a story to tell you too.” There was a senator, Bill Proxmire from Wisconsin who liked to make fun of science but was also a good environmentalist. She said, “1200 reprints that’s pretty good, but Proxmire asked me for 200,000 reprints of something I’d written for the NYT on the importance of water conservation, and he wanted to send that out to every voter in the state of Wisconsin” I said, “Mother, I am never going to get into another discussion of this sort again.” They were two very different audiences, and hers was possibly a more important one. [emphasis mine]"

Gladwell on genetic advantages

Nice Gladwell's piece on the New Yorker on genetic advantages in sports.

"In “The Sports Gene,” there are countless tales like this, examples of all the ways that the greatest athletes are different from the rest of us. They respond more effectively to training. The shape of their bodies is optimized for certain kinds of athletic activities. They carry genes that put them far ahead of ordinary athletes."

This is pretty clear, as I a said before anyone with half a brain can notice differences. People with agenda say everyone has the same potential. We do not. Physiological and morpholological differences are not easy to notice at the very top level, just because they are all exceptional, they are all outliers. But morpholological and physiological differences between top competitors and the lower-tier competitors/amateurs/hobbyists are clearly visible. You simply do not have the body structure/size to be a world-class javelin thrower, sprinter, shot-putter(now, do you think you have the same genetic potential?), long-distance runner, etc. There are non-responders to athletic stimuli and super-responders. There are people getting injured every second step and people with super tolerance to high volume workouts/competitions.

It is the same for a range of other "skills", from solving mathematical problems, to be at ease with learning new languages (surprisingly I have never seen studies testing whether the ability to learn programming languages is correlated with the ability to learn foreign languages, do they exist?), to just be good-looking, or "naturally" in decent shape.

For guys who jumped on the strange "we have all pretty much equal potential" bandwagon, just Open you Eyes (I,II).

Read the whole thing.